Genetics And Cell Biology Flashcards
Describe features of prokaryotes and eukaryotes
Prokaryotes:
- 2 groups or domains: archaea and bacteria
- no organelles
- no nucleus
- DNA with circular genome
- most diverse kind of cells
Eukaryotes:
- have discrete organelles
- have a nucleus (membrane bound structure containing DNA)
- have mitochondria
- have others such as Golgi and endoplasmic reticulum and lysosomes etc
- different types of cells for different functions
Draw a labelled diagram of a cell membrane
See lecture 1
Label a diagram of a mammalian cell
See lecture 1
Define cellular homeostasis
the property of a system, especially a living organism, to regulate its internal environment so as to maintain a stable, constant condition
Why do cells maintain homeostasis
Key things (like temperature, pH, osmolality, ionic concentrations etc) have to be kept in narrow tolerances
How is homeostasis maintained
- alter properties
- programmed cell death (apoptosis) necessary in multicellular animals
- infected or unhealthy cells “commit suicide” (altruism)
How many bonds are between adenine and thymine
2
How many bonds are between cytosine and guanine
3
Describe how covalent bonds and ionic bonds allow for stable arrangement of atoms
Both form strong bonds
Covalent bonds: between 2 non-metals and similar electronegativity
Ionic bonds: between metal and non- metals with different electronegativity
What are homopolymers
Polymers that are made of many copies of the same molecule
What are heteropolymers
Polymers created from different assemblies of different building blocks
What are the four main polymers found in cells? Give a brief description of each
- Polysaccharides: polymers of sugars - typically homopolymers
- Fats/lipids: polymers of carbons with other groups attached
- Nucleic acids: polymers of nucleotide bases in specific sequences ( heteropolymers)
- Proteins: polymers of 20 different amino acids in specific sequences (heteropolymers)
Describe the key components of sugars
- simplest are monosaccharides- (CH2O)n
- can be drawn as chains or rings - alpha and beta links (hydroxyl group on the carbon that carries aldehyde or ketone can rapidly change from one position to the other)
- disaccharides are simple polysaccharides (formed by glycosidic bonds)
- large linear and branched molecules can be made from simple repeating units - short chains are called oligosaccharides and long chains are called polysaccharides eg cellulose and glycogen
- glycogen is the stable storage form of glucose in the body
- cell surface glycoproteins are proteins with sugar on top
- one sugar group determines the difference between the ABO blood groups
How do you form sucrose, maltose and lactose
Sucrose = glucose + fructose Maltose = glucose + glucose Lactose = glucose + galactose
Describe the key properties of fatty acids
- components of cell membranes
- stored in the cytoplasm as triacylglcerol - can be released from it when a cell needs energy (done via acetyl CoA)
- saturated fats have no double bonds (solids and not very reactive)
- unsaturated fats have double bonds (don’t pack well and are quite reactive + they are oils)
- phospholipids aggregate to form cell membranes
- proteins are embedded in the plasma membrane lipid bilayer (can have many key roles eg transporters, anchors, receptors, enzymes)
What does amphipathic mean
Both hydrophilic and hydrophobic regions
Describe the key properties of nucleic acids
- form nucleotides
- basis of DNA and chromosomes
- nucleotides perform a variety of functions in cells
1. Carry chemical energy in their easily hydrolysed phosphoanhydride bonds
2. Combine with other groups to form coenzymes
3. Used as signalling molecules in the cell
Draw the general formula for an amino acid
See lecture 2 slide 36
Give two examples of diseases caused by protein assembly going wrong. Briefly describe each
- Cystic fibrosis: mutations in Cl- ion channel cause a misfolding of the channel that prevents correct Cl- transport
- Alzheimer’s disease: misfolding and aggregation of a protein called b-amyloid
Sketch a labelled diagram of a double stranded DNA molecule. To which end are new bases added
See lecture 3 slide 7
What is the sugar in RNA and what is it in DNA
RNA = ribose DNA = deoxyribose
What group the bases in DNA and RNA into purines and pyrimidines
Purines: Adenine and Guanine
Pyrimidines: cytosine, thymine and uracil
Draw a simple labelled diagram of DNA replication at the replication fork
See lecture 3 slide 13
What is released when a base is added during DNA synthesis
Pyrophosphate
P2O7^4-